Practice manipulating strings in the context of creating a new computer system user account.
Concepts: Invoking methods, parameters, return values, String methods, Math.random()
Textbook: 3.2, 3.5
Ask the user to enter their full name, which they then enter all at once at a single prompt. Their name must contain at least two words (that is, one internal space), but may contain more. (Don't let tricky users get by you by starting or ending their name with a space. Consider using the trim() method to prevent this.)
Print out the user's first name and their last name.
Then print out a username for the user. The username should be comprised of the first letter of their first name, and then up to 7 letters of their last name. (That is, a username cannot be longer than 8 characters, though it may be shorter.) The username should be all lowercase.
Then print out an initial password. This should be consist of a random digit, the user's first name uppercased, and two more random digits.
Each of the four outputs--first name, last name, username, and password--should be on their own line, clearly labeled. Labels should end in a ":" or "=", though spaces before or after this character are allowed.
Extra credit:
A real user account creator would need to prevent names from containing tabs, punctuation, and other special characters. Since there is no easy String method to check for this sort of thing, you would need to use a loop to check that each character is acceptable. Since we have not covered loops yet, this is not required.
However, for those interested in attempting this for extra credit: your program should report an error if the name contains anything other than letters or spaces. (Hint: see the Character class in the API, particularly the isLetter method.)
D:\TA\grading\A08>java ZtomaszeA08 For a new account, enter your full name: Superman Sorry, but your full name must include at least two words. D:\TA\grading\A08>java ZtomaszeA08 For a new account, enter your full name: Clark Kent First name: Clark Last name: Kent Username: ckent Password: 8CLARK15 D:\TA\grading\A08>java ZtomaszeA08 For a new account, enter your full name: Zach M Tomaszewski First name: Zach Last name: Tomaszewski Username: ztomasze Password: 3ZACH30 D:\TA\grading\A08>java ZtomaszeA08 For a new account, enter your full name: p t barnum First name: p Last name: barnum Username: pbarnum Password: 1P66 D:\TA\grading\A08>java ZtomaszeA08 For a new account, enter your full name: Illegal. Chars@ Sorry, but your full name must contain only letters and spaces.
The last execution is an example of the extra credit checking for illegal characters.
Upload your UsernameA08.java file to Tamarin.
CharSequence) and complicated features (such as regular expressions) that we won't even cover in this class. But you don't need to use all the methods. You only need to learn the methods we discussed in lab: equals, equalsIgnoreCase, length, charAt, indexOf, lastIndexOf, substring, trim, toUpperCase, toLowercase. And you won't even need all of those to complete this particular assignment. (If you do find some other String methods you'd like to use that aren't in this list, though, feel free to do so.)
isEmpty() method though.
java -version on the command line.) There is one String method that some students find--isEmpty()--that was added in Java 1.6. If you use this method, your code will probably compile on your machine, but it won't compile when you upload it to Tamarin.
Therefore, I'm asking that you don't use this method in your code. Two alternatives to str.isEmpty() are str.length() == 0 and str.equals("")
next(). (Well, you could if you used a loop, but this is actually more complicated and doesn't give you practice with String methods.) Instead, use nextLine() to read in the full name. Trim the full name with trim() to remove any spaces at the beginning or end of the string.
indexOf, and then take a substring from the beginning of the string to that position. This substring is the first name. (If there is no space to be found, it means the user entered only one word, or even none at all. In this case, indexOf will return -1 as the position of the first space.)
trim, indexOf, lastIndexOf, substring, and (possibly) length.
So, to detect one name, you need to use an if statement. The best place for this is right after you find the index of the first (or last, if you do that first) space. Remember indexOf will return -1 if it can't find what you're looking for. So, if firstSpace == -1, then there was no space, and thus not two words (assuming you trimmed the string before looking for a space, of course).
(Note that you could catch a StringIndexOutOfBoundsException here instead. However, this is bad practice. It's better to use an if statement as I just described to avoid generating the SIOOBE in the first place. Catching a SIOOBE when there is no space will also hide other potential indexing errors, such as when you get to forming the username, and thus make it harder to debug your own code.)
//read in name
name = name.trim();
//if (name contains no spaces) then:
//print error message: user entered nothing or only one name
//else:
//the name is valid, so start processing it
//the rest of your code goes here....
}
length method. If it's 7 or fewer characters long, you can just add the whole last name to the username; otherwise (else), you'll need to take a substring of only the first 7 characters.